Electrokinetic Velocity Of Non-ferromagnetic Particles At Oil-water Interface

The solid particles produced by the friction of machinery and equipment in lubricating oil are the main pollution sources of oil.This is also an important factor which causes the failure of machinery and equipment.The detection and separation of solid particles in oil is of great significance to detect the wear of ships,automobiles,machine tools and other mechanical equipment.In addition,it can also monitor the running state of the device and issue early warning of equipment failure in time.How to realize the detection of particles in oil accurately and quickly is an important research area.This paper mainly studied the electrokinetic velocity of non-ferromagnetic particles at oilwater interface,aiming at clarifying the influence of electric intensity,particle size and particle density on the electrokinetic velocity of particles at oil-water interface,and providing a certain theoretical basis for the design of a new particle detection device.The main research contents are as follows:(1)The contact angles of different types of non-ferromagnetic particles at oil-water interface were measured by a lateral observation system.The particles were spherical copper particles with diameters of 20μm,30μm,40μm,50μm,60μm and spherical aluminum particles with diameters of 30μm,40μm,50μm,60μm.Furthermore,the effects of particle density and size on the contact angle were analyzed according to the vertical force of particles at oil-water interface.The experimental results showed that the larger the density of the particle with the same size,the smaller the contact angle at oil-water interface.The larger the size of the particle with the same density,the greater the contact angle at oil-water interface.(2)Based on the principle of electric double layer,the effects of electric intensity,particle density and particle size on the electrokinetic velocity of particles at oil-water interface without considering the boundary influence were investigated.The experimental results showed that particles move towards the positive electrode after the electric field was applied.The strength of the applied electric field and the density of particles were the main factors affecting the electrokinetic velocity of particles at the oil-water interface.The electrokinetic velocity of particles increased with the increase of the intensity of the applied electric field,but decreased with the increase of the density of particles.There was no significant difference in the electrokinetic velocity of particles when the size of particles changed.(3)Experiments on the electrokinetic velocity of non-ferromagnetic particles at oil-water interface were carried out in a two-layer micro-channel.The electrokinetic velocity of particles in the micro-channel and the effect of sodium chloride solution on the electrokinetic velocity of particles were studied.The experimental results showed that the influence of particle density and electric intensity on the electrokinetic velocity of particles at oil-water interface in microchannel was the same as that without considering the influence of boundary.The electrokinetic velocity increased with the increase of electric intensity,decreased with the increase of particles density.The electrokinetic velocity of particles in the microchannel was affected by the electroosmotic flow of the water-wall interface.After the electric field was applied,particles at oil-water interface of the micro-channel moved to the positive electrode for a short time and then change the direction of movement to the negative electrode until they became stable.The velocity was smaller than that without the boundary effect,but the electric intensity was much greater than that under the infinite boundary condition.Particles at 1m M Na Cl solution-oil interface of the micro-channel moved towards the negative electrode until stable,and the direction of movement did not change.In this thesis,the main factors affecting the electrokinetic velocity of non-ferromagnetic particles at oil-water interface were determined.The electrokinetic velocity of particles in microchannel was investigated.The influence of sodium chloride solution on the electrokinetic velocity of particles was clarified.It provided a theoretical basis for the realization of the detection and separation of particles in oil in micro-channel,and was helpful for the further research on new efficient detection and separation technology of particles in oil.